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Search Results: 1 - 10 of 323660 matches for " Peter J. Kremer "
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Mesenchymal Stem Cell Conditioning Promotes Rat Oligodendroglial Cell Maturation
Janusz Joachim Jadasz, David Kremer, Peter G?ttle, Nevena Tzekova, Julia Domke, Francisco J. Rivera, James Adjaye, Hans-Peter Hartung, Ludwig Aigner, Patrick Küry
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071814
Abstract: Oligodendroglial progenitor/precursor cells (OPCs) represent the main cellular source for the generation of new myelinating oligodendrocytes in the adult central nervous system (CNS). In demyelinating diseases such as multiple sclerosis (MS) myelin repair activities based on recruitment, activation and differentiation of resident OPCs can be observed. However, the overall degree of successful remyelination is limited and the existence of an MS-derived anti-oligodendrogenic milieu prevents OPCs from contributing to myelin repair. It is therefore of considerable interest to understand oligodendroglial homeostasis and maturation processes in order to enable the development of remyelination therapies. Mesenchymal stem cells (MSC) have been shown to exert positive immunomodulatory effects, reduce demyelination, increase neuroprotection and to promote adult neural stem cell differentiation towards the oligodendroglial lineage. We here addressed whether MSC secreted factors can boost the OPC’s oligodendrogenic capacity in a myelin non-permissive environment. To this end, we analyzed cellular morphologies, expression and regulation of key factors involved in oligodendroglial fate and maturation of primary rat cells upon incubation with MSC-conditioned medium. This demonstrated that MSC-derived soluble factors promote and accelerate oligodendroglial differentiation, even under astrocytic endorsing conditions. Accelerated maturation resulted in elevated levels of myelin expression, reduced glial fibrillary acidic protein expression and was accompanied by downregulation of prominent inhibitory differentiation factors such as Id2 and Id4. We thus conclude that apart from their suggested application as potential anti-inflammatory and immunomodulatory MS treatment, these cells might also be exploited to support endogenous myelin repair activities.
A Prospective Study of Diet Quality and Mental Health in Adolescents
Felice N. Jacka, Peter J. Kremer, Michael Berk, Andrea M. de Silva-Sanigorski, Marjorie Moodie, Eva R. Leslie, Julie A. Pasco, Boyd A. Swinburn
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024805
Abstract: Objectives A number of cross-sectional and prospective studies have now been published demonstrating inverse relationships between diet quality and the common mental disorders in adults. However, there are no existing prospective studies of this association in adolescents, the onset period of most disorders, limiting inferences regarding possible causal relationships. Methods In this study, 3040 Australian adolescents, aged 11–18 years at baseline, were measured in 2005–6 and 2007–8. Information on diet and mental health was collected by self-report and anthropometric data by trained researchers. Results There were cross-sectional, dose response relationships identified between measures of both healthy (positive) and unhealthy (inverse) diets and scores on the emotional subscale of the Pediatric Quality of Life Inventory (PedsQL), where higher scores mean better mental health, before and after adjustments for age, gender, socio-economic status, dieting behaviours, body mass index and physical activity. Higher healthy diet scores at baseline also predicted higher PedsQL scores at follow-up, while higher unhealthy diet scores at baseline predicted lower PedsQL scores at follow-up. Improvements in diet quality were mirrored by improvements in mental health over the follow-up period, while deteriorating diet quality was associated with poorer psychological functioning. Finally, results did not support the reverse causality hypothesis. Conclusion This study highlights the importance of diet in adolescence and its potential role in modifying mental health over the life course. Given that the majority of common mental health problems first manifest in adolescence, intervention studies are now required to test the effectiveness of preventing the common mental disorders through dietary modification.
A complex pattern of chemokine receptor expression is seen in osteosarcoma
Irene von Luettichau, Stephan Segerer, Alexandra Wechselberger, Mike Notohamiprodjo, Michaela Nathrath, Markus Kremer, Anna Henger, Roghieh Djafarzadeh, Stefan Burdach, Ralf Huss, Peter J Nelson
BMC Cancer , 2008, DOI: 10.1186/1471-2407-8-23
Abstract: The overall level of chemokine receptor mRNA expression was determined using TaqMan RT-PCR of microdissected archival patient biopsy samples. Expression was then verified at the protein level by immunohistochemistry using a series of receptor specific antibody reagents to elucidate the cellular association of expression.Expression at the RNA level was found for most of the tested receptors. CCR1 expression was found on infiltrating mononuclear and polynuclear giant cells in the tumor. Cells associated with the lining of intratumoral vessels were shown to express CCR4. Infiltrating mononuclear cells and tumor cells both showed expression of the receptor CCR5, while CCR7 was predominantly expressed by the mononuclear infiltrate. CCR10 was only very rarely detected in few scattered infiltrating cells.Our data elucidate for the first time the cellular context of chemokine receptor expression in osteosarcoma. This is an important issue for better understanding potential chemokine/chemokine receptor function in the complex biologic processes that underlie the development and progression of osteosarcoma. Our data support the suggested involvement of chemokines and their receptors in diverse aspects of the biology of osteosarcoma, but also contradict aspects of previous reports describing the expression of these receptors in this tumor.Osteosarcoma is a primary tumor of the bone that accounts for 5% of childhood cancers and represents the fifth most frequent tumor in young adults [1]. In 15–20% of cases metastasis are present at the time of diagnosis. An additional 20–25% of the patients develop metastasis during the course of disease and have a very poor prognosis despite achievements in multimodal therapy [1]. Currently osteosarcoma is classified according to histological criteria with osteoblastic, chondroblastic and fibroblastic being the most frequent predominant histological elements [2]. The prognosis for patients is predicted by evaluating their response to preopera
Exciton fine-structure splitting of telecom wavelength single quantum dots: statistics and external strain tuning
Luca Sapienza,Ralph N. E. Malein,Christopher E. Kuklewicz,Peter E. Kremer,Kartik Srinivasan,Andrew Griffiths,Edmund Clarke,Ming Gong,Richard J. Warburton,Brian D. Gerardot
Physics , 2013, DOI: 10.1103/PhysRevB.88.155330
Abstract: In a charge tunable device, we investigate the fine structure splitting of neutral excitons in single long-wavelength (1.1\mu m < \lambda < 1.3 \mu m) InGaAs quantum dots as a function of external uniaxial strain. Nominal fine structure splittings between 16 and 136 \mu eV are measured and manipulated. We observe varied response of the splitting to the external strain, including positive and negative tuning slopes, different tuning ranges, and linear and parabolic dependencies, indicating that these physical parameters depend strongly on the unique microscopic structure of the individual quantum dot. To better understand the experimental results, we apply a phenomenological model describing the exciton polarization and fine-structure splitting under uniaxial strain. The model predicts that, with an increased experimental strain tuning range, the fine-structure can be effectively canceled for select telecom wavelength dots using uniaxial strain. These results are promising for the generation of on-demand entangled photon pairs at telecom wavelengths.
Canine Adenovirus Type 2 Vector Generation via I-Sce1-Mediated Intracellular Genome Release
Sandy Ibanes, Eric J. Kremer
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071032
Abstract: When canine adenovirus type 2 (CAdV-2, or also commonly referred to as CAV-2) vectors are injected into the brain parenchyma they preferentially transduce neurons, are capable of efficient axonal transport to afferent regions, and allow transgene expression for at last >1 yr. Yet, translating these data into a user-friendly vector platform has been limited because CAV-2 vector generation is challenging. Generation of E1-deleted adenovirus vectors often requires transfection of linear DNA fragments of >30 kb containing the vector genome into an E1-transcomplementing cell line. In contrast to human adenovirus type 5 vector generation, CAV-2 vector generation is less efficient due, in part, to a reduced ability to initiate replication and poor transfectibility of canine cells with large, linear DNA fragments. To improve CAV-2 vector generation, we generated an E1-transcomplementing cell line expressing the estrogen receptor (ER) fused to I-SceI, a yeast meganuclease, and plasmids containing the I-SceI recognition sites flanking the CAV-2 vector genome. Using transfection of supercoiled plasmid and intracellular genome release via 4-OH-tamoxifen-induced nuclear translocation of I-SceI, we improved CAV-2 vector titers 1,000 fold, and in turn increased the efficacy of CAV-2 vector generation.
An Update on Canine Adenovirus Type 2 and Its Vectors
Thierry Bru,Sara Salinas,Eric J. Kremer
Viruses , 2010, DOI: 10.3390/v2092134
Abstract: Adenovirus vectors have significant potential for long- or short-term gene transfer. Preclinical and clinical studies using human derived adenoviruses (HAd) have demonstrated the feasibility of flexible hybrid vector designs, robust expression and induction of protective immunity. However, clinical use of HAd vectors can, under some conditions, be limited by pre-existing vector immunity. Pre-existing humoral and cellular anti-capsid immunity limits the efficacy and duration of transgene expression and is poorly circumvented by injections of larger doses and immuno-suppressing drugs. This review updates canine adenovirus serotype 2 (CAV-2, also known as CAdV-2) biology and gives an overview of the generation of early region 1 (E1)-deleted to helper-dependent (HD) CAV-2 vectors. We also summarize the essential characteristics concerning their interaction with the anti-HAd memory immune responses in humans, the preferential transduction of neurons, and its high level of retrograde axonal transport in the central and peripheral nervous system. CAV-2 vectors are particularly interesting tools to study the pathophysiology and potential treatment of neurodegenerative diseases, as anti-tumoral and anti-viral vaccines, tracer of synaptic junctions, oncolytic virus and as a platform to generate chimeric vectors.
A model for a non-minimally coupled scalar field interacting with dark matter
Binder, J. B.;Kremer, G. M.;
Brazilian Journal of Physics , 2005, DOI: 10.1590/S0103-97332005000700003
Abstract: in this work we investigate the evolution of a universe consisted of a scalar field, a dark matter field and non-interacting baryonic matter and radiation. the scalar field, which plays the role of dark energy, is non-minimally coupled to space-time curvature, and drives the universe to a present accelerated expansion. the non-relativistic dark matter field interacts directly with the dark energy and has a pressure which follows from a thermodynamic theory. we show that this model can reproduce the expected behavior of the density parameters, deceleration parameter and luminosity distance.
A model for a non-minimally coupled scalar field interacting with dark matter
J. B. Binder,G. M. Kremer
Physics , 2006,
Abstract: In this work we investigate the evolution of a Universe consisted of a scalar field, a dark matter field and non-interacting baryonic matter and radiation. The scalar field, which plays the role of dark energy, is non-minimally coupled to space-time curvature, and drives the Universe to a present accelerated expansion. The non-relativistic dark matter field interacts directly with the dark energy and has a pressure which follows from a thermodynamic theory. We show that this model can reproduce the expected behavior of the density parameters, deceleration parameter and luminosity distance.
Model for a Universe described by a non-minimally coupled scalar field and interacting dark matter
J. B. Binder,G. M. Kremer
Physics , 2006, DOI: 10.1007/s10714-006-0268-3
Abstract: In this work it is investigated the evolution of a Universe where a scalar field, non-minimally coupled to space-time curvature, plays the role of quintessence and drives the Universe to a present accelerated expansion. A non-relativistic dark matter constituent that interacts directly with dark energy is also considered, where the dark matter particle mass is assumed to be proportional to the value of the scalar field. Two models for dark matter pressure are considered: the usual one, pressureless, and another that comes from a thermodynamic theory and relates the pressure with the coupling between the scalar field and the curvature scalar. Although the model has a strong dependence on the initial conditions, it is shown that the mixture consisted of dark components plus baryonic matter and radiation can reproduce the expected red-shift behavior of the deceleration parameter, density parameters and luminosity distance.
Adenovirus Tales: From the Cell Surface to the Nuclear Pore Complex
Eric J. Kremer,Glen R. Nemerow
PLOS Pathogens , 2015, DOI: 10.1371/journal.ppat.1004821
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